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The Mainz Basin ends in Bingen am Rhein; the Rhine continues as "Middle Rhine" into the Rhine Gorge in the Rhenish Slate Mountains. In this sections the river falls from 77.4 m above sea level to 50.4 m. On the left, is located the mountain ranges of Hunsrück and Eifel, on the right Taunus and Westerwald. According to geologists, the characteristic narrow valley form was created by erosion by the river while the surrounding landscape was lifted (see water gap). Major tributaries in this section are the Lahn and the Moselle. They join the Rhine near Koblenz, for the right and left respectively. Almost the entire length of the Middle Rhine River runs in the German state of Rhineland-Palatinate. The dominant economic sectors in the Middle Rhine area are viniculture and tourism. The Rhine Gorge between Rüdesheim am Rhein and Koblenz is listed as a UNESCO World Heritage Site. Near Sankt Goarshausen, the Rhine flows around the famous rock Lorelei. With its outstanding architectural monuments, the slopes full of vines, settlements crowded on the narrow river banks and scores of castles lined up along the top of the steep slopes, the Middle Rhine Valley can be considered the epitome of the Rhine romanticism. Lower Rhine Main article: Lower Rhine Low water in Düsseldorf The Lower Rhine at Emmerich In Bonn, where the Sieg flows into the Rhine, the Rhine enters the North German Plain and turns into the Lower Rhine. The Lower Rhine falls from 50 m to 12 m. The main tributaries on this stretch are the Ruhr and the Lippe. Like the Upper Rhine, the Lower Rhine used to meander until engineering created a solid river bed. Because the levees are some distance from the river, at high tide the Lower Rhine has more room for widening than the Upper Rhine. The Lower Rhine flows through North Rhine-Westphalia. Its banks are usually heavily populated and industrialized, in particular the agglomerations Cologne, Düsseldorf and Ruhr area. Here the Rhine flows through the largest conurbation in Germany, the Rhine-Ruhr region. One of the most important cities in this region is Duisburg with the largest river port in Europe (Duisport). The region downstream of Duisburg is more agricultural. In Wesel, 30 km downstream of Duisburg, is located the western end of the second east-west shipping route, the Wesel-Datteln Canal, which runs parallel to the Lippe. Between Emmerich and Cleves the Emmerich Rhine Bridge, the longest suspension bridge in Germany, crosses the 400 m wide river. Near Krefeld, the river crosses the Uerdingen line, the line which separates the areas where Low German and High German are spoken. Delta Main article: Rhine–Meuse–Scheldt delta The central and northern parts of the Rhine-Meuse delta Changing the Meuse estuary in 1904: light blue old course, dark blue today's course Partition of Rhine and Meuse water among the various branches of their delta The Rhine-Meuse Delta, the most important natural region of the Netherlands begins near Millingen aan de Rijn, close to the Dutch-German border with the division of the Rhine into Waal and Nederrijn. Since the Rhine contributes most of the water, the shorter term Rhine Delta is commonly used. However, this name is also used for the river delta where the Rhine flows into Lake Constance, so it is clearer to call the larger one Rhine-Meuse delta, or even Rhine–Meuse–Scheldt delta, as the Scheldt ends in the same delta. The shape of the Rhine delta is determined by two bifurcations: first, at Millingen aan de Rijn, the Rhine splits into Waal and Pannerdens Kanaal, which changes its name to Nederrijn at Angeren, and second near Arnhem, the IJssel branches off from the Nederrijn. This creates three main flows, two of which change names rather often. The largest and southern main branch begins as Waal and continues as Boven Merwede ("Upper Merwede"), Beneden Merwede ("Lower Merwede"), Noord River ("North River"), Nieuwe Maas ("New Meuse"), Het Scheur ("the Rip") and Nieuwe Waterweg ("New Waterway"). The middle flow begins as Nederrijn, then changes into Lek, then joins the Noord, thereby forming Nieuwe Maas. The northern flow keeps the name IJssel until it flows into Lake IJsselmeer. Three more flows carry significant amounts of water: the Nieuwe Merwede ("New Merwede"), which branches off from the southern branch where it changes from Boven to Beneden Merwede; the Oude Maas ("Old Meuse"), which branches off from the southern branch where it changes from Beneden Merwede into Noord, and Dordtse Kil, which branches off from Oude Maas. Before the St. Elizabeth's flood (1421), the Meuse flowed just south of today's line Merwede-Oude Maas to the North Sea and formed an archipelago-like estuary with Waal and Lek. This system of numerous bays, estuary-like extended rivers, many islands and constant changes of the coastline, is hard to imagine today. From 1421 to 1904, the Meuse and Waal merged further upstream at Gorinchem to form Merwede. For flood protection reasons, the Meuse was separated from the Waal through a lock and diverted into a new outlet called "Bergse Maas", then Amer and then flows into the former bay Hollands Diep. The northwestern part of the estuary (around Hook of Holland), is still called Maasmond ("Meuse Mouth"), ignoring the fact that it now carries only water from the Rhine. This might explain the confusing naming of the various branches. The hydrography of the current delta is characterized by the delta's main arms, disconnected arms (Hollandse IJssel, Linge, Vecht, etc.) and smaller rivers and streams. Many rivers have been closed ("dammed") and now serve as drainage channels for the numerous polders. The construction of Delta Works changed the Delta in the second half of the 20th Century fundamentally. Currently Rhine water runs into the sea, or into former marine bays now separated from the sea, in five places, namely at the mouths of the Nieuwe Merwede, Nieuwe Waterway (Nieuwe Maas), Dordtse Kil, Spui and IJssel. The Rhine-Meuse Delta is a tidal delta, shaped not only by the sedimentation of the rivers, but also by tidal currents. This meant that high tide formed a serious risk because strong tidal currents could tear huge areas of land into the sea. Before the construction of the Delta Works, tidal influence was palpable up to Nijmegen, and even today, after the regulatory action of the Delta Works, the tide acts far inland. At the Waal, for example, the most landward tidal influence can be detected between Brakel and Zaltbommel. Country passings and borders During its course from the Alps to the North Sea, the Rhine passes through four countries and constitutes six different country borders. On the various parts: the Vorderrhein lies entirely within Switzerland, while at least one tributary to Hinterrhein, Reno di Lei originates in Italy, but is not considered a part of the Rhein proper. the Alpine Rhine flows within Switzerland till Sargans, from which it becomes the border between Switzerland (to the West) and Liechtenstein (to the East) until Oberriet, and the river never flows within Liechtenstein. It then becomes the border between Switzerland (to the West) and Austria (to the East) until Diepoldsau where the modern and straight course enters Switzerland, while the original course Alter Rhein makes a bend to the East and continues as the Swiss-Austrian border until the confluence at Widnau. From here the river continues as the border until Lustenau, where the modern and straight course enters Austria (the only part of the river that flows within Austria), while the original course makes a bend to the West and continues as the border, until both courses enters Lake Constance. the first half of Seerhein, between the upper and lower body of Lake Constance, flows within Germany (and the city of Konstanz), while the second is the German (to the North) - Swiss (to the South) frontier. the first parts of the High Rhine, from Lake Constance to Altholz, the river alternates flowing within Switzerland and being the German-Swiss frontier (three times each). From Altholz the river is the German - Swiss border until Basel, where it enters Switzerland for the last time. the Upper Rhine is the border between France (to the West) and Switzerland (to the East) for a short distance, from Basel to Hunningue. Here it becomes the Franco (to the West) - German (to the East) frontier until Au am Rhein. Hence, the main course of the Rhine never flows within France, although some river canals do. From here the river flows within Germany. the Middle Rhine flows entirely within Germany. the Lower Rhine flows within Germany until Emmerich am Rhein, where it becomes the border between The Netherlands (to the North) and Germany (to the South). At Millingen aan de Rijn the river enters the Netherlands and continues to the North Sea. Railway crossings Main article: List of bridges over the Rhine Tributaries Tributaries from source to mouth: Left Thur River (Switzerland) Töss River Aar (Aare) Birs Birsig Ill (France) Moder River Lauter (Rhine) Nahe River Moselle River Nette (Rhine) Ahr Erft Meuse River (joins part of the Rhine in the shared delta) Right Hinterrhein River Ill (Austria) Schussen Wutach River Alb Wiese Elz (Rhine) Kinzig (Rhine) Rench Acher Murg Alb Pfinz Neckar Main Lahn Wied River Sieg Wupper Düssel Ruhr Emscher Lippe River Oude IJssel Berkel Former distributaries Order: panning North to South through the Western Netherlands: Vecht (Utrecht) (minor channel in Roman times, flowing into former Zuider Zee lagoon) Kromme Rijn – Oude Rijn (Utrecht and South Holland) (main channel in Roman times, dammed in the 12th century) Hollandse IJssel (formed after Roman times, dammed in the 13th century AD) Linge (big channel in Roman times, dammed in the 14th century AD) De Biesbosch-area (initiated by AD 1421–1424 storm surges and river floods, by-passed since the digging of Nieuwe Merwede canal in AD 1904) Canals Order: upstream to downstream: Rhine–Main–Danube Canal – southeastern Germany Grand Canal d'Alsace – eastern France Rhine-Herne Canal – northwest Germany, connection to the Dortmund-Ems Canal and the Mittellandkanal Maas-Waal Canal – eastcentral Netherlands Amsterdam-Rhine Canal – central Netherlands Scheldt-Rhine Canal – southwest Netherlands Canal of Drusus Geologic history Alpine orogeny Schematic cross section of the Upper Rhine Graben. The Rhine flows from the Alps to the North Sea Basin; the geography and geology of its present day watershed has been developing, since the Alpine orogeny began. In southern Europe, the stage was set in the Triassic Period of the Mesozoic Era, with the opening of the Tethys Ocean, between the Eurasian and African tectonic plates, between about 240 MBP and 220 MBP (million years before present). The present Mediterranean Sea descends from this somewhat larger Tethys sea. At about 180 MBP, in the Jurassic Period, the two plates reversed direction and began to compress the Tethys floor, causing it to be subducted under Eurasia and pushing up the edge of the latter plate in the Alpine Orogeny of the Oligocene and Miocene Periods. Several microplates were caught in the squeeze and rotated or were pushed laterally, generating the individual features of Mediterranean geography: Iberia pushed up the Pyrenees; Italy, the Alps, and Anatolia, moving west, the mountains of Greece and the islands. The compression and orogeny continue today, as shown by the ongoing raising of the mountains a small amount each year and the active volcanoes. In northern Europe, the North Sea Basin had formed during the Triassic and Jurassic periods and continued to be a sediment receiving basin since. In between the zone of Alpine orogeny and North Sea Basin subsidence, remained highlands resulting from an earlier orogeny (Variscan), such as the Ardennes, Eifel and Vosges. From the Eocene onwards, the ongoing Alpine orogeny caused a N–S rift system to develop in this zone. The main elements of this rift are the Upper Rhine Graben, in southwest Germany and eastern France and the Lower Rhine Embayment, in northwest Germany and the southeastern Netherlands. By the time of the Miocene, a river system had developed in the Upper Rhine Graben, that continued northward and is considered the first Rhine river. At that time, it did not yet carry discharge from the Alps; instead, the watersheds of the Rhone and Danube drained the northern flanks of the Alps. Stream capture The watershed of the Rhine reaches into the Alps today, but it did not start out that way.[13] In the Miocene period, the watershed of the Rhine reached south, only to the Eifel and Westerwald hills, about 450 km (280 mi) north of the Alps. The Rhine then had the Sieg as a tributary, but not yet the Moselle River. The northern Alps were then drained by the Danube. Through stream capture, the Rhine extended its watershed southward. By the Pliocene period, the Rhine had captured streams down to the Vosges Mountains, including the Mosel, the Main and the Neckar. The northern Alps were then drained by the Rhone. By the early Pleistocene period, the Rhine had captured most of its current Alpine watershed from the Rhône, including the Aar. Since that time, the Rhine has added the watershed above Lake Constance (Vorderrhein, Hinterrhein, Alpenrhein; captured from the Rhône), the upper reaches of the Main, beyond Schweinfurt and the Vosges Mountains, captured from the Meuse River, to its watershed. Around 2.5 million years ago (ending 11,600 years ago) was the geological period of the Ice Ages. Since approximately 600,000 years ago, six major Ice Ages have occurred, in which sea level dropped 120 m (390 ft) and much of the continental margins became exposed. In the Early Pleistocene, the Rhine followed a course to the northwest, through the present North Sea. During the so-called Anglian glaciation (~450,000 yr BP, marine oxygen isotope stage 12), the northern part of the present North Sea was blocked by the ice and a large lake developed, that overflowed through the English Channel. This caused the Rhine's course to be diverted through the English Channel. Since then, during glacial times, the river mouth was located offshore of Brest, France and rivers, like the Thames and the Seine, became tributaries to the Rhine. During interglacials, when sea level rose to approximately the present level, the Rhine built deltas, in what is now the Netherlands. The last glacial ran from ~74,000 (BP = Before Present), until the end of the Pleistocene (~11,600 BP). In northwest Europe, it saw two very cold phases, peaking around 70,000 BP and around 29,000–24,000 BP. The last phase slightly predates the global last ice age maximum (Last Glacial Maximum). During this time, the lower Rhine flowed roughly west through the Netherlands and extended to the southwest, through the English Channel and finally, to the Atlantic Ocean. The English Channel, the Irish Channel and most of the North Sea were dry land, mainly because sea level was approximately 120 m (390 ft) lower than today. Most of the Rhine's current course was not under the ice during the last Ice Age; although, its source must still have been a glacier. A tundra, with Ice Age flora and fauna, stretched across middle Europe, from Asia to the Atlantic Ocean. Such was the case during the Last Glacial Maximum, ca. 22,000–14,000 yr BP, when ice-sheets covered Scandinavia, the Baltics, Scotland and the Alps, but left the space between as open tundra. The loess or wind-blown dust over that tundra, settled in and around the Rhine Valley, contributing to its current agricultural usefulness. End of the last ice age As northwest Europe slowly began to warm up from 22,000 years ago onward, frozen subsoil and expanded alpine glaciers began to thaw and fall-winter snow covers melted in spring. Much of the discharge was routed to the Rhine and its downstream extension.[14] Rapid warming and changes of vegetation, to open forest, began about 13,000 BP. By 9000 BP, Europe was fully forested. With globally shrinking ice-cover, ocean water levels rose and the English Channel and North Sea re-inundated. Meltwater, adding to the ocean and land subsidence, drowned the former coasts of Europe transgressionally. About 11000 yr ago, the Rhine estuary was in the Strait of Dover. There remained some dry land in the southern North Sea, connecting mainland Europe to Britain. About 9000 yr ago, that last divide was overtopped / dissected. These events were well within the residence of man. Since 7500 yr ago, a situation with tides and currents, very similar to present has existed. Rates of sea-level rise had dropped so far, that natural sedimentation by the Rhine and coastal processes together, could compensate the transgression by the sea; in the last 7000 years, the coast line was roughly at the same location. In the southern North Sea, due to ongoing tectonic subsidence, the sea level is still rising, at the rate of about 1–3 cm (0.39–1.18 in) per century (1 metre or 39 inches in last 3000 years). About 7000–5000 BP, a general warming encouraged migration up the Danube and down the Rhine, by peoples to the east, perhaps encouraged by the sudden massive expansion of the Black Sea, as the Mediterranean Sea burst into it through the Bosporus, about 7500 BP. Holocene delta At the begin of the Holocene (~11,700 years ago), the Rhine occupied its Late-Glacial valley. As a meandering river, it reworked its ice-age braidplain. As sea-level continued to rise in the Netherlands, the formation of the Holocene Rhine-Meuse delta began (~8,000 years ago). Coeval absolute sea-level rise and tectonic subsidence have strongly influenced delta evolution. Other factors of importance to the shape of the delta are the local tectonic activities of the Peel Boundary Fault, the substrate and geomorphology, as inherited from the Last Glacial and the coastal-marine dynamics, such as barrier and tidal inlet formations.[15] Since ~3000 yr BP (= years Before Present), human impact is seen in the delta. As a result of increasing land clearance (Bronze Age agriculture), in the upland areas (central Germany), the sediment load of the Rhine River has strongly increased[16] and delta growth has sped up.[17] This caused increased flooding and sedimentation, ending peat formation in the delta. The shifting of river channels to new locations, on the floodplain (termed avulsion), was the main process distributing sediment across the subrecent delta. Over the past 6000 years, approximately 80 avulsions have occurred.[13] Direct human impact in the delta started with peat mining, for salt and fuel, from Roman times onward. This was followed by embankment, of the major distributaries and damming of minor distributaries, which took place in the 11–13th century AD. Thereafter, canals were dug, bends were short cut and groynes were built, to prevent the river's channels from migrating or silting up. At present, the branches Waal and Nederrijn-Lek discharge to the North Sea, through the former Meuse estuary, near Rotterdam. The river IJssel branch flows to the north and enters the IJsselmeer, formerly the Zuider Zee brackish lagoon; however, since 1932, a freshwater lake. The discharge of the Rhine is divided among three branches: the River Waal (6/9 of total discharge), the River Nederrijn – Lek (2/9 of total discharge) and the River IJssel (1/9 of total discharge). This discharge distribution has been maintained since 1709, by river engineering works, including the digging of the Pannerdens canal and since the 20th century, with the help of weirs in the Nederrijn river. |
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